A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic res onance imaging (MRI) using a small prototype MR compatible PET scanner (McP ET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofr equency interference or susceptibility effects caused by operation of the P ET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequ ency interference from the MR system were investigated. Biological tissue a nd a T-2-weighted spin echo sequence were used to examine susceptibility ar tefacts due to components of the McPET scanner (scintillator, optical fibre s) situated in the MR field of view. A range of commonly used MR pulse sequ ences was studied while acquiring PET data to look for possible artefacts i n either the PET or MR images. Other than a small loss in signal-to-noise u sing gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is poss ible to acquire PET and MR images simultaneously, without any significant a rtefacts or loss in image quality, using our prototype MR compatible PET sc anner.